Because of its outstanding mechanical and electronic properties and unique transfer flexibility, graphene is ideal for miniature all-in-fiber nanoelectromechanical systems (NEMS) in ultrasensitive sensing applications; however, its application in magnetic detection is limited because of the lack of magnetic-optic response. Here, we demonstrate a high spatial resolution fiber-optic magnetic field sensor based on Lorentz force in a pseudo–magnetic-response quasi-static graphene NEMS. The ultra-compact design of this all-fiber-based sensor is achieved by integrating a hybrid gold-graphene membrane and two gold electrodes onto the hollow endface of a single-mode fiber. An electrical current flowing through the suspended membrane in a perpendicular magnetic field can generate Lorentz force to cause a nanoscale deformation of the membrane. The sensor has a much higher spatial resolution, which is nanometer-scale longitudinally, compared with conventional optical fiber magnetic sensors.

In this study, we experimentally demonstrate a miniature fiber thermometer based on tip-integrated ZnO-nanowire-nanograting. The sensor has a diameter less than 1 µm and the length of the Bragg grating is sub-10 µm. The ZnO-nanowire-nanograting is sensitive to the environmental temperature change. Thus, the intensity of the light whose wavelength is in the rising or falling region of the nanograting spectrum will vary with the shift in wavelength due to change in temperature. Taking one wavelength (655 nm) in the rise linear region of the nanograting spectrum, a sensitivity of 0.066 nW/°C in the air is achieved experimentally. The proposed temperature sensor has the superiorities of compactness, stableness, and easy fabrication compared to regular fiber grating sensors, offering great potential for detecting inside minimal volume environments.

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